Method of sterilizing

ABSTRACT

A bio-air sterilization system and method of use thereof is provided that can remove and render benign harmful contaminants and particulates, such as bacteria, viruses, and molds, from air within an enclosed area, as well as, in principle, from the exposed surfaces located within the enclosed area. In one aspect, the sterilization system includes a self contained, mobile sterilization unit that includes at least an ultraviolet array, an air flow control mechanism for diverting the air flow within the system through either a filter or through an ozone removal zone, an ozone generator, and a blower apparatus to pull the air through the system and out through ports, such as a nozzle system, to the surrounding environment.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a U.S. national phase application filed under 35U.S.C. §371 of International Application PCT/US2008/054400, filed onFeb. 20, 2008, designating the United States, which claims benefit ofU.S. Provisional Application No. 60/902,502, filed Feb. 22, 2007, whichare hereby incorporated herein by reference in their entirety.

FIELD OF THE INVENTION

The present invention relates to an air filtration and cleaning systemand, in particular, to an air sterilization unit and related methods forremoving harmful biological contaminants and particulates from anenclosed area.

BACKGROUND OF THE INVENTION

It has been a long-standing goal in the field of air filtration systemsto remove harmful contaminants and particulates, such as bacteria,viruses and molds, from air within an enclosed area, as well as from thesurfaces located within the enclosed area, thus maintaining a safeworkplace for individuals.

People spend about 75 to about 90 percent of their time indoors wherethey are exposed to a growing number of health-threatening indoorpollutants. These pollutants can be categorized into three groups:biological contaminants, such as bacteria, viruses, and molds; toxicgases and fumes given off by furniture, carpeting, etc.; andparticulates, such as dust and smoke. Approximately half of the majoroffice buildings have contaminated heating, ventilation, and airconditioning (HVAC) systems. If not properly maintained, the HVACsystems are a hotbed for the growth of molds and bacteria, regardless ofthe age of the building. Occupants of these buildings can be expected tosuffer from symptoms related to exposure to these health-threateningindoor pollutants. The problem of health-threatening indoor pollutantsis exacerbated when the building is a health facility where not only arethere a greater number of harmful health-threatening pollutants present,but occupants of the health facility may be more susceptible to maladiescaused by these health-threatening pollutants.

A known solution for removing harmful contaminants from ambient air isthe use of air purifiers. Air purifiers use a scientifically advancedprocess that combines the power of germicidal ultraviolet (UV) light,purifying hydroxyl, activated oxygen, and photo-ionization for purifyingair and sanitizing an area. However, existing air purifiers do not usethe multiple approach of pre-ionization of the incoming air, highefficiency particulate (HEPA) filtration, and sterilization by use ofultraviolet nm lamps for a more complete solution. Further, mostexisting air purifiers use small ultraviolet lamps that do not allowadequate time required for sterilization.

Another approach for removing harmful contaminants from surfaces is theuse of chlorine to clean water and surfaces. However, chlorine may leaveharmful residuals within the drinking water and chlorine also cannot bereadily generated on site. The chlorine must be shipped to the site frommanufacturers located a distance away from the point of need. Duringemergency situations, proper handling of chlorine containers may beimpractical.

Ozone has been used in municipal drinking water systems to purify andkill microorganisms and bacteria. Ozone, however, is a powerful oxidantand its exposure to humans generally needs to be limited. The U.S.Occupational Safety and Health Administration limits ozone exposure inthe workplace to less than 0.1 ppm over an 8 hour period. When used topurify fluids, however, reduction to acceptable levels is generally nota concern because ozone has a half-life of about 8 to about 30 minutesin water (depending on temperature). Therefore, any ozone used to purifymunicipal drinking water will have decayed to acceptable levels longbefore it is exposed to human consumption. Use of ozone to sterilize anenclosed air space presents other challenges because the half-life ofozone in air can be as high as about 36 to about 72 hours (depending ontemperature). Therefore, if ozone is used to sterilize an enclosed area,depending on the concentration used to sterilize that area, the spacemay not be suitable for human contact for over a day and a half.

Attempts have been made to sterilize rooms using ozone generation, suchas hospital size rooms and larger (i.e., about 1000 ft³ or larger), butsuch previous attempts have either used large, fixed systems or have notbeen able to generate sufficient concentrations of ozone to kill anydetectable levels of contaminates. Large, fixed systems only sterilizethe room to which they are fixed and provide no sterilization to roomsthat are not associated with the ozone. Therefore, fixed systems requiremultiple, expensive systems and increased capital and operating costs.Prior systems have also been ineffective at providing sufficient levelsof detectable biocide activity using airborne ozone in hospital sizedrooms.

Notwithstanding these and other proposals, a need remains for asterilization system, especially a mobile system, that effectivelyprovides the user with an ability to sterilize an ambient environment,such as a patient room or mobile operating room in a turnkey manner. Inparticular, a need remains for a mobile system for filtering outparticulates, safely destroying biological contaminants such as by ozonegeneration, effectively converting the ozone to highly ionized ambientair, and providing for the convenient, efficient removal of the ozonefrom the environment about the mobile system.

SUMMARY AND OBJECTS OF THE INVENTION

These and other objectives are met by the present system that provides abio-air sterilization system, that can remove and render benign harmfulcontaminants, pathogens, and particulates, such as bacteria, viruses,and molds, from air within an enclosed area, as well as, in principle,from the exposed surfaces located within the enclosed area. It ispreferred that the sterilization system is capable of providingsufficient sterilization to remove and render benign harmfulcontaminates and particulates in an enclosed area, such as a hospitalsized room, which can be, in some cases, greater than about 1000 ft³ or,in other cases, greater than about 2000 ft³. However, the systemsdescribed herein will also sterilize smaller rooms and enclosures.

In one aspect, the sterilization system includes a self-contained,mobile sterilization unit that includes an air intake, a filter for theair (preferably a HEPA filter), an ultraviolet array, an air flowcontrol mechanism for diverting the air flow within the system througheither an additional filter (preferably a HEPA filter) or through anozone removal zone, a further filter, an ozone generator, a blowerapparatus to pull the air through the system and out through ports, suchas a nozzle system, to the surrounding environment. Since the blowerapparatus pulls air into the sterilizer system, the sterilizationfunction can be maintained on a continuous duty cycle, or other dutycycle, for a period of time, especially a pre-determined selected periodof time, when the air circulating within the system is not divertedthrough an ozone removal zone. When ozonated air is diverted through theozone removal zone, the ozone generator is preferably off-line.

In another aspect of the system, a method for sterilizing an environmentutilizing a self-contained mobile sterilization unit includes operatinga sterilization system in the environment to be sterilized for suchperiod of time as desired to achieve sterilization or the desired degreeof sterilization. By one approach, the method includes transporting aself-contained mobile sterilization unit to a predetermined space;drawing an air flow into the mobile unit; optionally, exposing the airflow to ultraviolet radiation having a maximum disinfecting level up toand including the ability to kill tuberculosis and/or hepatitis A; anddosing an amount of ozone to the air flow sufficient to provide ozoneconcentration to the predetermined space to sterilize the predeterminedspace. In one case, the amount of ozone can be dosed up to about 1 gramper hour (in other cases, up to about 10 grams per hour). In anothercase, the ozone can be maintained up to about 20 ppm (in other cases,about 1 to about 10 ppm) for a predetermined time, such as, but notlimited to, up to about 8 hours (generally about 1 to about 2 hours andin some cases about 30 minutes or less). It will be appreciated theozone dosing amounts, exposure duration, and concentration levels canvary depending on the contaminants to be removed, size of the enclosedspace, environmental parameters, and other factors. After thepredetermined exposure duration, the ozone is removed from the enclosedspace. After such sterilization cycle is complete, the mobilesterilization unit can be removed from the space.

In another aspect of the system, a method of measuring and controllingthe application of ozone is provided that is particularly useful for aself-contained, mobile sterilization system. By one approach, the methodincludes first measuring an environmental parameter, such as, but notlimited to, temperature (wet or dry bulb), relative humidity, pressure,dew point, other psychrometric parameters, or combinations thereof.Next, a particular agent or contaminant to be sterilized is selected.The agent or contaminant can include, for example, various bacteria,mold, virus, fungi, other contaminants, and combinations thereof. Aftermeasuring the environmental parameter and selecting the agent, theminimum ozone dosage and minimum application duration are determinedbased on the environmental parameters and agent. If needed, the variousenvironmental parameters can be adjusted (i.e., adjusting temperature,humidity, and the like) to modify the dosage or application time. Then,a concentration of ozone per unit time factor (i.e., ppm-minute) isdetermined that is sufficient based on the space to be sterilized,environmental parameters, and selected agent(s) and/or contaminant(s) tokill such agents or contaminants. During the dosing exposure duration,the concentration of ozone (or environmental parameter) can becontinuously monitored (i.e., every 10 seconds, every minute, every 5minutes, etc.) and the dosing rate (or environmental parameter) can beadjusted based on the measured concentration (or measured environmentalparameter) in order to generally maintain the concentration of ozone perunit time.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is an illustration of one embodiment of the invention that iscapable of being wheeled into an environment to be sterilized.

FIG. 2 illustrates air flow paths through an embodiment of the presentinvention with respect to certain elements of the exemplarysterilization system.

FIG. 3 is cross section along a horizontal axis of an embodiment of anexemplary sterilizer system.

FIG. 4 is a cross section along a vertical axis of an embodiment of anexemplary sterilizer system.

FIG. 5 shows partially overlaid louvered plates from an air valve in adisassembled form.

FIG. 6 shows an exemplary air valve.

FIG. 7 shows an exemplary air valve in an actuated position.

FIG. 8 shows in an edge view a cross member, a biased post, and parts ofthe valve plates in an exemplary air valve.

FIG. 9 shows an exemplary ozone generating element, such as a plasmapack.

FIG. 10 is an exemplary anode and cathode arrangement in the ozonegenerating element.

FIG. 11 is an exemplary arrangement of an exemplary ozone generatingelement and blower fan.

FIG. 12 is a plot of ozone concentration and temperature as a functionof time.

FIG. 13 is a cross-sectional side view showing a comparativeconfiguration for an ozone generating element.

FIG. 14 is a rear elevational view generally along lines A-A of theexemplary ozone generating element of FIG. 13.

FIG. 15 is a rear elevational view of an exemplary inventiveconfiguration for an ozone generating element.

FIG. 16 is a cross-sectional side view of the exemplary inventiveconfiguration of FIG. 15.

FIG. 17 is a front elevational view of the exemplary inventiveconfiguration of FIG. 15.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

In a preferred embodiment, a self-contained, mobile sterilizer system 20as generally illustrated in FIG. 1 is mounted on wheels 14, such ascastors, to facilitate its being transportable and placed in position inan environment to be sterilized. As shown in FIG. 1, an embodiment ofthe sterilization system 20 has a front panel with a display 13,indicator elements 10, an on-off switch 11, and other display indicia orswitches 12 (such as for manual override). The switch 11 can be a keyoperated switch or push button style switch. Display 13 can include aprogrammable logic controller 15 for the sterilization system, or thecontroller 15 can be a separate component, but is in operativeconnection with the display 13 and the components to be controlled inthe sterilization system 20. Display 13 can comprise a touch screen. Thesterilization system 20 has a closed housing with a pair of exit ports16 shown as nozzle(s) 9 and an intake 17 for air through a filter 1 (seeFIG. 2 and FIG. 3). Although a pair of nozzles 9 is shown in FIG. 1, theactual number of nozzles 9 is not restricted to that number. One of thenozzles 9 is shown in FIG. 1 as being on a side panel to sterilizationsystem 20 to indicate that location is not restricted. Thus, forinstance, it will be appreciated that nozzles can be positionedside-by-side on the top surface. Electrical power cord(s), electricaloutlets, light sockets, wiring, internal electrical connections and thelike are not shown and it is understood that these can be positioned andlocated consistent with a particular design as will be appreciated by aperson skilled in the art based on this application. It will beappreciated that access panels can be provided, such as in the topsurface and or on the side, back, and/or front panels of thesterilization system 20, to permit access to components within thehousing for service and/or replacement (for example, elements in UVarray, filters, etc.).

The preferred mobile sterilizer system 20 includes at least twofunctions and several modes. In general, such a system 20 may have atleast three modes. The general functions are to sterilize a room usingozone alone or using a combination of ultraviolet light and ozone asdisinfecting agents, or optionally with an ion generator (such as aso-called hydroxyl generator). To this end, the mobile system 20 mayinclude in a single, transportable housing 21 an ozone generator 6, anultraviolet light source 2, and an optional hydroxyl generator 10. Itwill be appreciated that the Figures illustrate various arrangement ofthese components in the housing 21. Such arrangements are only exemplaryand can vary as needed for a particular situation.

Ozone is a powerful gaseous chemical that can destroy all germs whenused in proper dosages. Ozone can be used as a disinfectant of choice tosterilize a room. Ozone is a noxious material. Ozone is thus preferablyused for such purpose when the room is unoccupied. Since ozone is a gas,it can penetrate most areas within a room and kill surface and airbornebacteria, mold, or viruses. While ozone can sterilize a room via airapplication, it is most commonly used as a sterilizing agent in thewater treatment industry. Heretofore, ozone has not apparently not beenregarded as disinfectant characterized as having utility in atmosphericsterilization because of concerns associated with gases, namely as a gasozone becomes unwieldy in open environments and can disperse toorapidly.

One of the advantages of the mobile sterilizer system 20 is its abilityto be transported to an enclosed space and sterilize the enclosed space,such as a hospital sized room of about 1000 ft³ or larger (preferably,about 2000 ft³ or larger), and also cleanse the space of ozone after thespace is subjected to ozone treatment. The application or dosing of theroom can be selected and visually displayed, such as with the display 13with user inputs, and controlled such as by programmable means, such asthe programmable logic controller 15, to set the dosing and duration ofdosing (ozone generation), as well as de-ozonation, and, if desired theoperation of the UV array. For example, an integrated timer in theprogrammable logic controller can be used to customize control of theozone generator's period of operation. The sterilization system 20 can,if desired, be fitted with a motion sensor 18 (FIG. 1) that de-activatesthe ozone generator 6 if someone should enter the enclosed area. It willbe appreciated that any alarm or notification means can be provided,such by an electronic connection to a network or othercomputer/communications system to alert the operator, which can includesignal transmission to a remote receiving device such as a telephone(VOIP, cell, landline, etc.) or paging device. The signal transmissionfor notification is not limited and includes e-mail notification andso-called instant or text messaging, among others. Electronic connectionincludes wireless. An audible alarm or visual alarm can also beprovided, such as to signal when de-ozonation is completed. Whiledisplay and programmable means may be presently preferred, a manualsystem can, in principle, be used as well.

The ozone removal is accomplished in an ozone removal zone 4. The ozoneremoval zone 4 can comprise a catalytic filter element, an ionized gasgenerator, and/or an electromagnetic radiation generator containedwithin the housing 21 of the system 20 to thereby promote an efficient,effective method to destroy the ozone and remove it from the room in ashort amount of time so that the room can be quickly re-occupied.Preferably, ozone is removed from the enclosed space in about 2 hours orless and, in some cases, in about 30 to about 60 minutes. By oneapproach, available information indicates that the ozone removal zone 4is configured to reduce the concentration in the enclosed space to about0.1 ppm or less in the removal time. It will be appreciated that removalof ozone can vary depending on the concentration, room size, and otherfactors.

The system 20 can also have the ultraviolet light source 2, which caninclude a plurality of ultraviolet lamps. For instance, in oneembodiment, the ultraviolet light source 2 is comprised of an array ofultraviolet lamps emitting light at about 254 nanometers wavelength,which can provide a powerful disinfectant function. Other wavelengthsmay also be used as needed. The science of UV light disinfecting is wellknown. There are many manufacturers of UV bulbs. They have establisheddosing levels for UV light. UV lamps and their general attributes aredescribed in a publication from Phillips, US Purification—ApplicationInformation, Perfection Preserved (Phillips), the complete disclosure ofwhich is incorporated herein by reference. The UV light source can bechosen and designed to have a minimum disinfecting level of up to andincluding the ability to kill tuberculosis and/or Hepatitis A. The UVlight source can be operated in combination with the ozone subsystem orindependently of the ozone portion of the system. The UV light source iswithin the housing for the sterilization system and in one embodimentmay function to kill certain airborne pathogen contaminates, and thusmay be operated even if the sterilization system 20 is located in a roomthat is occupied.

The sterilization system 20 can operate using the ultraviolet arrayhaving sufficient emission to disinfect air circulating within thesystem in combination with the internal ozone generator 6. In principle,there may be a synergistic effect obtained when using ozone and UV incombination as disinfecting agents simultaneously. For example,sterilization of the enclosed space may occur in less time.

As shown in FIG. 2, air 11 is the working fluid in the mobile, roomsterilizer 20. The air path design is responsible for the ozone deliveryto the room. Ozone introduced into a circulating air flow can be laterremoved as depicted when the circulating air is diverted to path “b” inFIG. 2. In FIG. 2, air enters the apparatus through a filter 1,sometimes called an intake filter. By preference, the filter 1 removesdust to protect a secondary or down stream filter 5 from becomingclogged and saturated with particulates. The filter 1 (and/or the filter5) is preferably antimicrobial and can be treated to provide additionalgermicidal action, i.e., can help kill germs. Alternatively, filter 1(and/or filter 5) can be a HEPA (High Efficiency Particulate Air) filterthat is capable of removing, in some cases, up to at least 99.9 percentof airborne particulate down to about 0.3 microns in diameter. However,the efficiency of the HEPA filter may vary. Next, the air passes throughthe ultraviolet light source 2. By preference, the ultraviolet source 2is designed to irradiate the air with a dosage of UV radiation effectiveat killing germs, including tuberculosis and Hepatitis A. As shown inFIG. 3, the light source 2 can be an array of three UV generators,although the numbers and orientation are not limited to the exemplaryembodiment as shown. For instance, the array may have more than three UVgenerators in the light source 2.

As shown in FIG. 3, the ultraviolet light 2 in the sterilizer system 20can be within a chamber 12 that is configured to allow the air tocirculate past the UV lights with a sufficient dwell time to be exposedto the ultraviolet radiation whereby a combination of the UV lightintensity plus time of exposure may be sufficient to extirpate thepathogen (germs, etc.) or at least provide a desired degree ofsterilization. By preference, the air path meanders through said chamber12 and there may be baffles 13 (not shown in FIG. 2, but see FIG. 3).The baffles 13 are preferably spatially disposed and shaped within saidchamber 12 so that the air has a desired dwell time (duration ofexposure to the UV), while preferably flowing at a relatively uniformvelocity past through the ultraviolet light 2.

As shown in FIG. 2, the air flows through an air valve 3. The air valve3 functions as a diverter valve directing the air directly either viapath “a” thence to filter 5 and to the ozone generator 6 or via path “b”through a de-ozonation zone 7 (and presumably with the that may includea plenum 8 and is introduced into the environment via the nozzles 9surrounding the sterilization system 20. When the sterilization system20 is operational, a blower system 7 draws the air in through the intakefilter 1, whereby a continuous flow of air can be obtained through thesystem. The blower system 7 is preferably sized to ensure appropriatemetered air flow and circulation within the sterilization system 20, andthus it should preferably be such as to account for pressure dropsbecause of air flow through the filters 1 or 5, through the de-ozonationzone 4, or around baffles 13 in the chamber 12 having the UV source 2(so as to ensure a desired dwell time for exposure to UV), etc. Inprinciple, the blower system 7 can be chosen so as to draw air throughsterilization system 20 at a fixed speed, at selected or programmedspeeds (bi-speed or three speed, as examples) or at a variables speedduring operation. Air flow through the system 20 can range, for example,from about 60 to about 400 CFM. It will be appreciated, however, thatsuch flow rates are exemplary and may vary depending on the particularsystem. Nozzle(s) 9 or other suitable structure can be in flowcommunication with the plenum 8 and can be used to direct the air, suchas ozonated air, from the sterilization system 20 to the surroundingenvironment, such as into a room (for example, a bathroom, surgery room,recovery room, or the like), or to a region of a room, such as a corner.

The air valve 3 directs air flow directly into the filter 5 via air path“a” while being closed to air path “b” so as to prevent air beingozonated from passing through ozone removal zone 4. The air valve 3 canbe actuated upon signal from the programmable logic controller 15 (notshown), which may have a manual override, to divert air to path “b”.

In one embodiment, the air valve 3 includes a stationary valve plate 40in slideable engagement relative to a moveable valve plate 50 as seen inFIGS. 5-8. The valve plates 40 and 50 have louvers 45 and 55 that arearranged so that moveable slide plate 50 can be either stationary (atrest) or slid relative to the stationary valve plate 40. Thus, therespective louvers 45 and 55 in said plates 40 and 50 are positioned sothat air flow is permitted in either of the above mentioned air flowpaths in FIG. 2, but not both at the same time. This is illustrated inFIG. 5 that shows plate 50 partially overlying a plate 40 from adisassembled air valve 3. FIG. 6 shows said plate 50 overlying plate 40to illustrate that air flow would be allowed via path “a”, but not path“b” when plate 50 is at rest when actuator 60 is not actuating. FIG. 7shows plate 40 manually slid upwardly relative to plate 50 to illustratewhen the air valve 3 is fully actuated the air path “a” is closed andthe air path “b” is opened. The rectangular cut out 56 in the center ofplate 50 fits over the actuator 60 (FIGS. 6 and 7) that can be mountedon plate 40, but also is sized to allow play so plate 50 can be movedrelative to plate 40 when actuator 60 is actuated. FIG. 8 shows aportion of an uninstalled exemplary air valve 3. An actuator 60 is usedto actuate a suitable mechanism that slides the moveable valve plate 50over the stationary valve plate 40. The actuator 60 can be a solenoidtype system or other suitable apparatus that is capable of sliding(moving) plate 50 relative to plate 40 from a position where therespective louvers of such facing plates allow only air path “a” to beopen to a second position whereby the louvers allow only air path “b” tobe open.

As shown in FIG. 7, the actuator 60 may be linked to a biasing element70, such as a spring, so that plate 50 returns to a first position whenactuator 60 is no longer ‘fired.’ It will be appreciated that thebiasing element 70 will have one end connected to plate 40 and the otherend connected to plate 50 as in FIG. 7. The actuator 60 is preferablyoperatively controllable via the programmable logic controller 15 forthe sterilization system 20. The actuator 60 is preferably operativelycontrolled by the controller 15 (programmable logic controller mentionedhereinabove), which may receive input from a sensor 30 (FIG. 3) totrigger the actuator 60, such as for activation or de-activation. Forexample, the actuator 60 may be automatically triggered to direct air tothe ozone removal zone 4 upon the sensor 30 detecting the presence of aperson in the room. It will be appreciated that the sensor 30 canadditionally be used to monitor the ozone concentration during theozonation step. Sensor 30 can be augmented or replaced by other sensorsmounted, for instance, to sense the ozone concentration in theenvironment within which the sterilization system 20 is placed. Suchother sensor or sensors can be mounted to be exposed on an exteriorsurface of the sterilization system 20.

The moveable valve plate 50 is preferably arranged and installed so oneof its surfaces faces the incoming flow towards air flow valve 3. Thisorientation may enable the moveable plate 50 to better seal against thestationary plate 40 by taking advantage of the pressure differentialcreated by the air flow. In addition to the valve 3 using the pressuredifferential to seal, the moveable valve plate 50 can be biased againstthe stationary plate 40. As shown in FIGS. 6 to 8, for example, pairs ofmembers 100 can be provided with biasing means, such as a spring ortorsion element 102 (FIG. 8), to bias plate 50 against plate 40. Themembers 100 fit within notched portions 58. Notches 58 are on both sideedges of plate 50, with notches 58 on one such side shown in FIG. 5. Anelement 90 can be used to connect pairs of biased members 100 (studs orposts, or the like) to provide more uniform biasing and to help maintainplate 50 in slideable, facing, but sealed relationship to plate 40. Theplates 40 and 50 may receive, if desired, a friction aid, preferably along lasting, non-volatile, non-particulate lubricant. For instance, inprinciple, the plates may have their facing surfaces Teflon coated, asone example. By preference, in an exemplary embodiment, the moveableplate 50 is thinner than the stationary plate 40. The plates 40 and 50can be made of metal, such as aluminum. It will be appreciated that thisembodiment of the air valve 3 is merely illustrative as other means forproviding air flow control between path “a” and path “b” will beapparent to a person skilled in the art in view of this specification.

The de-ozonation zone 4 comprises a de-ozonator 32, such as a filter asmentioned hereinabove. The filter may be comprised of, for example,manganese dioxide, manganese dioxide and copper oxide, or PPS fibers(polyphenylene sulfide fibers) sandwiched in a filter-like containment.An element 15 (i.e., baffle, wall, or other blockage) depicted in FIG. 2can be elbow-shaped and it ensures that the de-ozonation zone is notopen to air flowing along air path “a”. The element 15 is not limited toan elbow-shape. Air flows through the de-ozonation zone 4 through path“b”. By preference, the sterilization system 20 operates with airflowing along air path “a” during the ozonation stage and along air path“b” during the de-ozonation stage. Alternatively, the de-ozonator 30 mayalso include an electromagnetic ozone generator capable of generatingdiscrete bands of electromagnetic radiation sufficient, in principle, tocatalyze ozone or cause ozone to oxidize itself. While not wishing to belimited by theory, it is believed that some wavelengths greater thanabout 254 nanometers may be sufficient for the de-ozonator 4.

As shown in FIGS. 9 and 10, the exemplary ozone generator 6 can comprisea corona discharge ozone generator 60. The corona discharge ozonegenerator 60 makes use of a plurality of anode/cathode cells 62. Thecells 62 include a concentric assembly of a central high voltageelectrode 64, a ceramic dielectric 66 surrounding the electrode 64, andan outer perforated tube 68. Ozone is created when a gas (i.e., ambientair or oxygen) passes through a space 70 between the anode and cathodewhile a high voltage is applied across the anode and cathodearrangement. As the gas passes through the space 70 between the anodeand cathode, the electric field created by the voltage applied to theanode and cathode splits some oxygen molecules, and the released oxygenatoms react with oxygen molecules to form ozone. In particular, thecorona discharge pack 60 is constructed of a rolled stainless steel,perforated shell 68. A ceramic dielectric 66 is inserted into the shelland a working gap 70 is established between the ceramic dielectric 66and the shell 68 to support the corona discharge. Commercial low voltagepower is generally stepped-up to the high voltage necessary to createthe corona by a frequency/voltage inverter (not shown) before deliveryto the ceramic core. As it passes through the corona, the oxygen inambient air becomes excited and its oxygen molecules becomedisassociated. Some of the oxygen molecules recombine into ozone. Thecorona discharge ozone generator 60 is designed to produce ozone levelsadequate for the required room disinfection. For simplicity ofdescription, the following description may also refer to a “secondultraviolet lamp” and it is understood that the corona discharge ozonegenerator 60 can be substituted for the second ultraviolet lamp. Thecorona discharge or so-called plasma ozone generator can be a highfrequency system or a low frequency system.

The ozone generator 6 should be configured to generate sufficient ozoneto kill the selected contaminants in the selected space. In one example,available information indicates that a suitable ozone generator isconfigured to generate or dose up to about 1 gram ozone per hour (inother cases, up to about 10 grams per hour) in order to provide andmaintain an ozone concentration of up to about 20 ppm and, in somecases, about 1 to about 10 ppm ozone. It will be appreciated, however,that the dosing rate and concentration may vary depending on manyfactors as needed for a particular application.

In principle, it is believed that the level of ozone generation can beaffected by the amount and flow of air through the ozone generator 6. Byone approach, as shown in FIG. 11, a corona generator 60 is positionedwithin the ozone generator in an arrangement to providemulti-directional air flow 72 into and through the generator 60. In thismanner, it is believed that such multi-directional air flow 72 helpskeep the cells 62 cool and helps remove ozone from the space 70 thereby,in principle, permitting additional ozone to be generated in a moreefficient manner. While not wishing to be limited by theory, suchmulti-directional air flow can, in principle, double the ozone output ofthe generator 60. For example, available information suggests that sucha multi-direction air flow through the ozone generator can provide about50 to about 75 percent higher output of ozone from a plasma ozonegenerator.

The sterilized air containing ozone is then re-circulated back into theenvironment and through the above-described blower system 7. The roomair 11 is re-circulated or drawn back into the sterilization system 20to destroy additional airborne contaminants, including those which havebeen newly introduced into the enclosed area.

Once the sterilization system has performed the desired sterilization,the ozone generator 6 is shut off and the air valve 3 diverts aircirculating through the system 20 to the ozone removal zone 4, beforethe de-ozonated air is re-circulated to the surrounding environment. Thede-ozonation 4 is preferably performed until the ozone concentration isreduced to a sufficiently low level to make the area safe forinhabitants. By one approach, such level is about 0.1 ppm or less.Depending on the starting ozone concentration, the ozone removal zone 4is configured to remove ozone to the low levels (i.e., about 0.1 ppm orless) in about 2 hours or less, preferably about 1 hour or less, and, insome cases, about 30 minutes or less. The mobile system 20 isadvantageous, therefore, because downtime of the room, such as ahospital room, with high levels of ozone is minimized. The hospitalroom, for instance, can be sterilized and turned around for a newpatient in a short amount of time using the system 20.

The ozone level can be monitored by sensors within the sterilizationsystem as well as by ozone sensors exposed to the surroundingenvironment. FIG. 3 shows an exemplary sensor 30. Sensor 30 can be usedfor controlling an aspect of the operation of the sterilization system.The ozone sensor(s) 30 can be coupled to the programmable logiccontroller 15, or other suitable means. The sensor(s) 30 can determinethe ozone concentration and thus can be suitably employed to determinewhether to maintain ozone generation, whether to continue de-ozonation,and to increase or decrease the ozone dosing amount. The ozone generator6 can, if desired, include a timer, or can be controlled by theprogrammable logic controller 15 for the sterilization system 20. Itwill be appreciated that the system 20 can, if desired, be manuallycontrolled.

FIG. 3 is a top view showing the intake filter 1 and air circulationaround the UV source (UV devices 2) and the meandering air flow aroundthe baffles 13 before entering an ante chamber 31 having the sensor 30.The sensor 30 can be a suitable sensor board, including a mini-fan,logic means, and the like, as will be apparent to those skilled in theart from this description. Due to the cut-away aspect of FIG. 3, it willbe appreciated that element 16 is not depicted. In practice, there maybe top support plate extending across the interior side walls and UVelements 2 can depend from such support plate within the air flow aroundthe baffles 13 shown in FIG. 3. The support plate allows the UV lightsource 2 to be physically held in place and allows electrical wiring forthe array to be above the plate and shielded from UV light (and perhapsozone) when the sterilization system 20 is operational. As will beappreciated, the support plate, interior side walls of the sterilizationsystem will define the interior chamber 12 configured to allow the airto circulate past and be exposed to light generated by the UV generatingelements 2.

FIG. 4 shows an end view of the exemplary sterilization system 20 inwhich front panel(s) is removed. The system 20 may include the element15, which is a member that connects the de-ozonator 4 in sealingabutting engagement to the back side of plate 40. Element 16 is a soliddeflector member in this embodiment so that air from ozonation path “a”is directed towards filter 5. Element 16 also serves to separate theozone destruction zone 4 from filter 5. Element 17 is an electricalpanel in this embodiment. Electrical ballast can be mounted to element17 as can ozone generator 6. As shown, the ozone generator 6 is mountedso as to maximize air flow around and through it so that the circulatingair flow may cool the device as discussed previously. Element 16 keepsthe air flow to filter 5 regardless of whether air circulation is byeither ozonation path “a” or ozone removal path “b”. An air valve 3 isshown in side-view and will divert the air to path “a” or to path “b”,but not both during the operation of sterilization system 20.

Nozzle 9 can include a butterfly or other valving mechanism to controlthe flow of air. A shut off valve system can also prevent particulatesfrom falling into the sterilization system when it is not in use, or isbeing moved from one location to another.

In FIG. 2, a controller is not illustrated although it will be apparentto the person skilled in the art that a controller means, such as theprogrammable logic controller 15, can control the elements shown, and ispreferably capable of receiving program direction from user inputs tocontrol the operation of the sterilization system.

The present sterilization system 20 can be transported to any enclosedarea requiring the destruction of bacteria, viruses and odors. Forextremely large areas, two or more sterilization systems may be requiredand can operate concurrently. The present sterilization system 20 can beon wheels 14 to facilitate its being moved from one enclosed area toanother, or moved into a storage compartment. However, other modes oftransport may also be used such as, but not limited to, rails, guides,slides, castors, ramps, tracks, and the like. Transportable generallyrefers to a system that is configured and arranged and has a size andweight such that it can be moved by an individual of average size andweight, such as by pushing or carrying from room to room. It will beappreciated that the present invention can be applied to such systems asare described in U.S. Patent Application Publication US 2005/0186108A1,and that the present sterilization system 20 can be incorporated into amobile medical unit, such as a mobile medical unit described in U.S.Pat. No. 4,915,435, the complete disclosures of which are incorporatedherein by reference.

The system 20 also includes a method of measuring and controlling theapplication of ozone to sterilize a space using a controller with ozonesensing and the monitoring of various environmental parameters orcombinations thereof. The methods herein permit the ozone sterilizingprocess to sterilize the offending agents in a consistent manner becausea variety of parameters are selected, monitored, and/or controlled. Itwill be appreciated that various environmental variations, such as, butnot limited to the following characteristic in the space to besterilized can affect the sterilization process: room volume, materialspresent within the room (both solid and vapor), room's leakage rates,temperature, barometric pressure, and other psychrometric parameters.

The system 20, therefore, can measure any or all of a variety ofpsychrometric parameters so that the optimum dosage required tosterilize the room can be determined. The controller 15 can then assurethat the proper dosing of the room is accomplished. The controller canalso store a data base of dosages for each agent to be sterilized, suchas various kinds of bacteria, viruses, mold or fungi installed in a database along with dosage requirements to inactivate or kill such agents.The user of the controller 15 can then select the particular agent oragents that they wish to remove, and the machine will analyze and decideon the proper dosage requirement for the room. The dosing rate ofmicroorganisms varies as a function of many environmental parameters andthe data base will use this information to set the controller's dosagerate.

The system 20 can also estimate the amount of residual dosage that ispresent in the room's atmosphere prior to the time the controllerswitches processes and begins removing ozone. In principle, thisresidual ozone represents an additional source of ozone that iseffective in room sterilization and is not typically counted in the roomdosage. By using this residual ozone, the controller can minimize theoverall time that the room is under sterilization.

For purposes herein, the ozone dosage can be calculated using a valueknown as a “Cleo”. The total “Cleos” represent the total sterilizationvalue of ozone applied to the room. The Cleo Unit representsconcentration of ozone per unit time and is typically measured andcalculated from parts per million of ozone multiplied by the minutes ofozone exposure. The unit of a Cleo, therefore, is used to convey thisvalue and typically has units of parts per million-minutes (ppm-min).While a Cleo unit will vary based on many factors (i.e., contaminant,pathogen, room size, temperature, humidity, etc.), exemplary ranges canbe from about 300 to about 1000 ppm-minute. Such Cleo values aresuitable in many cases to kill about 99.9 percent Staphylococcus aureus.Since the concentration of ozone continuously varies during thesterilization process, the methods herein permit the monitoring andcontrol of the ozone dosing to enable determination and varying theozone dosing respondent to the measured parameters (such as ozoneconcentration and various environmental parameters).

The controller not only measures psychrometric parameters, but itpreferably can also control such parameters, such as, but not limitedto, temperature and humidity within a room. For example, while notwishing to be limited by theory, it is believed in principle that lowertemperatures, high pressures, and high relative humidity are moreeffective in killing organisms and other contaminants with ozone. Forexample, it is believed that at least about 50 percent and, in somecases, about 50 percent to about 75 percent (or higher) relativehumidity is more effective in ozone sterilization. As a result, themethods herein can measure room relative humidity and, if needed, add(or remove) moisture to desired levels for most efficient sterilization.In addition, it is believed that temperatures of about 12 to about 18°C. are more effective in generating sufficient quantities of ozoneneeded to sterilize the enclosed space. As a result, the methods hereincan also measure room temperature and, if needed, increase (or decrease)the temperature to desired ranges. By one approach, the method cancontinuously monitor and measure the environmental parameters. While theabove describes exemplary environmental parameters, it will beappreciated that such parameters may vary depending on the particularagent to be sterilized, room size, and other parameters.

Alternatively, the method may also vary the dosing amount to take intothe environmental parameters. That is, the dosing amount or duration canvary respondent to the various measured environmental parameters. Forexample, with a lower pressure or lower relative humidity, increaseddosage rates may be used. For higher temperatures, increase applicationdurations may be used.

The machine or controller will calculate the ozone dose to match a userapplied setting based on the measured parameter(s) and selected agents.Dosing also allows the user to minimize the time to sterilize a room bytaking advantage of total ozone resident in room throughout thesterilizing and the residual ozone present in the ozone reductionprocess. This is accomplished by predicting the total application timeand adding to it the predicted amount of ozone resident during the ozonereduction process.

The exact calculation of the Cleo unit generally involves using theinstantaneous measurement of ozone concentration in the room andaggregating or integrating it as a function of time. Alternatively,other less accurate methods of estimating the ozone dosage, may also beapplied. During a typical ozone cleansing cycle, the ozone dosingcalculation may be arrived at by measuring the ozone density in partsper million every minute and multiplying the value by one minute (othertime intervals may also be used). The resulting quantity would then besummed with the next dosing value, which calculated value would closelyapproximate the actual integration of the ozone concentration versustime curve. As a result, the ozone management system 20 preferablycontinuously monitors and projects the amount of ozone required to doseand kill the bacteria within a room based on the particular agentselected and various environmental parameters measured.

Advantages and embodiments of the concentrates described herein arefurther illustrated by the following examples; however, the particularconditions, flow schemes, materials and amounts thereof recited in theseexamples, as well as other conditions and details, should not beconstrued to unduly limit this method. All percentages are by weightunless otherwise indicated.

EXAMPLES Example 1

A study was completed to measure ozone concentration and temperatureover time in an enclosed chamber of about 2,000 ft³ (200 ft² chamberhaving a 10 foot high ceiling). The chamber was sealed from air enteringor leaving the chamber and fabricated out of walls made frompolyethylene.

An ozone generating element (Plasma Technologies Inc., Racine, Wis.) wasplaced in the enclosed chamber and an ozone sensor (Aerogual Ltd.,Auckland, New Zealand) measured the amount of ozone in the chamber overtime. A temperature sensor also concurrently measured the chamber airtemperature. A plot of ozone concentration and temperature over time isprovided in FIG. 12. Ozone was supplied at a rate of about 1 gram/hour.

As shown in FIG. 12, the ozone concentration reached about 3 to about 4ppm in about 15 minutes after ozone dosing commenced. After about 2hours of ozone dosing, the ozone generator was turned off and an ozoneremoval zone was activated. Ozone was removed with a manganese oxidecatalyst. After about 2 hours, the amount of ozone in the enclosedchamber was reduced to about 0.09 ppm.

Example 2

A study was completed using an exemplary sterilization system asdescribed herein using only the UV light source to kill airbornepathogens. A mixture of about 2500 to about 2600 CFU (colony formingunits) of Mycobacterium smegmatis (a tuberculous surrogate) was sprayedat the intake of the system. The system was then operated at about 96CFM and only the UV light source irradiated the air flow at about 254nanometers. At the output nozzle of the system, there were zero recordedCFUs. Samples were analyzed by Aerobiology Laboratory, Dulles, Va.).

Example 3

A study was completed to determine the ability of the sterilizationsystems described herein to kill pathogens using ozone. In one study,cultures containing about 7380 CFUs (culture forming units) ofAcinetobacter baumanii were placed in an enclosed room of about 2000 ft³of about 70° F. and about 50 percent relative humidity. Thesterilization system supplied about 5 ppm of ozone to the room from anozone generating unit (Plasma Technologies). After about 2 hours ofdosing, the culture had about 0 CFUs. In another study, culturescontaining about 7900 CFUs of Aspergillius fumigatus were placed in anenclosed room of about 2000 ft³ at about 70° F. and about 50 percentrelative humidity. The sterilization system supplied about 5 ppm ofozone to the room. After about 2 hours of dosing, the culture had about20 CFUs. Testing was completed at Aerobiology Laboratory

Example 4

A study was completed to determine the effect of air flow on the abilityof an ozone generator to provide ozone. In a comparative configuration,an ozone generating element 1000 (Plasma Technologies) was placed in aplenum 1002 as generally illustrated in FIG. 13 so that air 1004 canonly flow in a single direction (i.e., uni-directional air flow) throughthe ozone generator. The configuration of FIG. 13 was capable ofproviding about 0.6 grams of ozone per hour, with about 96 CFM air flowrate in a plenum of about 16 in². Ozone concentration was measureddownstream of the generating element 1000.

In one exemplary inventive configuration, an ozone generator 2000(Plasma Technologies) was placed on a mounting panel 2002 so that amulti-directional air flow 2004 could flow through the ozone generatorand then be concentrated through a narrowed orifice 2006 in the mountingpanel 2002 at the downstream end of the ozone generator 2000 asgenerally illustrated in FIG. 14. The orifice 2006 has a cross-sectionalarea of about 8 in². The configuration of FIG. 14 was capable ofproviding about 0.9 grams of ozone per hour, which is an improvementover the configuration of FIG. 13 of about 50 percent. It is believedthat even greater increases (up to about 75 percent or more) are alsopossible. Air flow rate was about 96 CFM and the plenum in this case hada cross-sectional area of about 64 in².

While not wishing to be limited by theory, it is believed that themulti-directional air flow through the generator and the use of thedownstream orifice imparts a shearing and/or turbulence on the air flowthrough the generator along with, in principle, a pressure drop andvelocity increase of the air. As a result, it is believed that thegenerated ozone can be removed from the ozone generator at a faster ratethereby allowing fresh oxygen to be drawn into the generator andconverted to ozone.

It will be understood that various changes in the details, materials,and arrangements of the methods, processes, and systems, which have beenherein described and illustrated in order to explain the nature of thesystem and methods therein, may be made by those skilled in the artwithin the principle and scope of the embodied method as expressed inthe appended claims.

1. A method of measuring and controlling the application of ozone tosterilize a predetermined space, the method comprising: measuring anenvironmental parameter of the predetermined space, the environmentalparameter including temperature, relative humidity, pressure, dew point,or combinations thereof; selecting a contaminant for sterilization, thecontaminant selected from the group consisting of bacteria, virus, mold,fungi, and combinations thereof; determining a minimum ozone dosage andminimum ozone application duration sufficient to inactivate the selectedcontaminant, the ozone dosage and the ozone application durationdependant on the measured environmental parameter and the contaminantselected for sterilization; determining a concentration of ozone perunit time sufficient to inactivate the selected contaminant dependant onthe minimum ozone dosage and minimum ozone application duration;supplying ozone to the predetermined space from an ozone generator, thesupplied ozone in an amount sufficient to generally achieve thedetermined concentration of ozone per unit time; monitoring ozoneconcentration in the predetermined space; monitoring the ozoneconcentration at a predetermined interval; and aggregating the monitoredozone concentrations at each predetermined interval to determine anoverall ozone concentration.
 2. The method of claim 1, wherein the ozoneis supplied in an amount up to about 10 grams per hour.
 3. The method ofclaim 1, wherein the supplied ozone is sufficient to provide up to about20 ppm ozone in the predetermined space having an air volume of about1000 ft³ or larger.
 4. The method of claim 1, further comprisingadjusting the amount of ozone supplied responsive to the monitored ozoneconcentration.
 5. The method of claim 1, further comprising adjustingthe ozone application duration responsive to the monitored ozoneconcentration.
 6. The method of claim 1, wherein after the ozoneapplication duration has elapsed, stopping supplying ozone to thepredetermined space and measuring a residual concentration of ozone inthe predetermined space.
 7. The method of claim 6, wherein after theozone application duration has elapsed, removing ozone from thepredetermined space.
 8. The method of claim 6, further comprising afterthe ozone application duration has elapsed, diverting air from thepredetermined space to an ozone removal zone for removal of the ozonefrom the predetermined space.
 9. The method of claim 1, furthercomprising after measuring the environmental parameter, adjusting theenvironmental parameter.
 10. The method of claim 9, wherein adjustingthe environmental parameter includes adding or removing moisture fromthe predetermined space to control relative humidity.
 11. The method ofclaim 10, wherein the relative humidity is controlled to a predeterminedrange based on the selected contaminant.
 12. The method of claim 9,wherein adjusting the environmental parameter includes increasing ordecreasing a temperature of the predetermined space.
 13. The method ofclaim 12, wherein the temperature is controlled to a predetermined rangebased on the selected contaminant.
 14. The method of claim 1, whereinthe environmental parameter is measured at a predetermined intervalthroughout the ozone application duration.